Bulgarian 7.62Rx54 Heavy Ball Observations/Questions

[brassell31]

Hi, all. First time posting on this forum. I have been collecting milsurp rifles off and on for 30 years, reloading and shooting and hunting with them. The last ten years of my employment before I retired was as a gunsmith/salesperson in a local gun shop. I got a lot of deals on milsurps there, some from estates where the inheritors did not want the guns left to them, some from people just looking for a little cash, and some from other collectors. One of the last things I aquired were two wood crates of Bulgarian 7.62Rx54 ammo along with a 1929 Mosin91/30 hex receiver rifle from an estate. I finally got around to shooting the rifle after 3 years of sitting in my gun safe using the Bulgarian ammo. I could not hit the target at 50 yards, and about 10% of the casings were rupturing near the base. Using a large sheet of paper, I found the bullets hitting everywhere at random! I bore scoped the rifle when I got home and discovered the bore was so pitted that the rifling was hard to see. Solved that mystery, and it's a shame since the rest of the rifle was armory refurbished and is all matching serial numbers.
Getting back to the Bulgarian ammo, I took a scoped Mosin of known accuracy and the best I could do with it was 3" groups at 50 yards. This rifle will generally shot 2" groups at 100 yards with reloads. The case is brass, the rim is beveled. The case markings are on the face, which is divided into 4 quadrants by lines. The top quadrant is a lion, left is "19", right is "48". I am assuming this is the date of manufacture, 1948. The bottom quadrant is a capital "B" followed by a lower case "o" with a vertical line through it. The one bullet I pulled weighed 184 grains, was boat tailed and magnetic, with a cannelure. There appears to have been a very light wash of a copper color on the bullet tip, hard to tell as they are all faded. It measures .308" in diameter. I measured ten other loaded rounds, all measured .308" but one, which measured .309" in diameter. Since it should be closer to .311" for this round, that could the reason for the lousy accuracy. As I mentioned, the bullets came in wood crates. There were two sealed metal tins in each crate. Each tin contains 250 rounds, the bullets in string wrapped paper packets of ten each. The tins have a pull tab that attaches to a metal ribbon around one end to open it. There is no writing on the tins, but there was a paper packing slip in the tin I opened. The splits from the ruptured cases were near the base and typically about 1/8" long. They ruptures occurred in both of the rifles I shot them through. The brass at the base up against the rim measures .480 - .482". My reloading manuals all show this measurement should be .489", Wikipedia .487".
Since that many cases rupturing doesn't give me warm fuzzies, I may pull some of the bullets that are all .308" and see how they shoot in my .308 Win. I don't plan on shooting this ammo "as is" anymore. Anyone else have any experience with this ammo?

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[Eaglelord17]

3" groups with surplus is pretty good. I have never been able to get better than about 4" at 100m with any of the 7.62x54r surplus I have used, but with handloads I have gotten groups of 1.5" and if I was a better shot I am sure it could be a bit better than that even.

I wouldn't get worried about rim size, if it chambers and ejects it is fine, that is the advantage of rimmed ammo it doesn't need to be perfect. The ruptures are more concerning though. Is that only happening on the first M91/30 or both of them. If its only the first one I would check to see if the chamber is fine on it.

[brassell31]

The 3" groups were at 50 yards. I have Abanian ammo that groups 2" easy with my scoped Mosin at 100 yards. Handloads do better. The brass was rupturing in both rifles. The measurements were the base of the brass just in front of the rim. I am going to compare the measurements to other Mosin ammo that I have. It could be that the Bulgarian brass is just old and brittle.